Method of providing sheet metal articles with louvers



Dec. 26, 1961 G. A. LYON 3,014,446

METHOD OF PROVIDING SHEET METAL ARTICLES WITH LOUVERS Filed May 22, 1956 e Sheets-Sheet 1 Egg GAURGZ' AABfRT AYO/l/ G. A. LYON Dec. 26, 1961 METHOD OF PROVIDING SHEET METAL ARTICLES WITH LOUVERS Dec. 26, 1961 3. A. LYON 3,014,446

METHOD OF PROVIDING sHEET METAL ARTICLES WITH LOUVERS Filed May 22, 1956 e Sheets-Sheet s day: @M 4%, 2 2

Dec. 26, 1961 G. A. LYON 3,014,446

armor) OF PROVIDING SHEET METAL ARTICLES WITH LOUVERS Filed May 22, 1956 6 Sheets-Sheet 4 fizazzim ZMW Dec. 26, 1961 G. A. LYON 3,014,446

METHOD OF PROVIDING SHEET METAL ARTICLES WITH LOUVERS Filed May 22, 1956 6 Sheets-Sheet 6 E12 i 11E awn 415m? 1 mm United States Patent Gfidce Patented Dec. 26, 1961 3,014,446 METHOD OF PROVIDING SHEET METAL ARTICLES WITH LOUVERS George Albert Lyon, Detroit, Mich, assignor to Lyon Incorporated, Detroit, Mich, a corporation of Delaware Filed May 22, 1956, Ser. No. 586,619

13 Claims. (Cl. 113-116) The present application is a continuation-impart of my following applications:

S.N. 311,933, filed September 27, 1952 SN. 345,193, filed March 27, 1953 SN. 345,195, filed March 27, 1953 S.N. 345,196, filed March 27, 1953 SN. 368,736, filed July 17, 1953 S.N. 368,737, filed July 17, 1953.

The present invention relates to improvements in making sheet metal articles, and more particularly concerns the shaping of such articles with air circulation promoting louver structure.

An important object of the present invention is to provide an improved method of providing louvers in sheet metal articles without the use of special louver shaping dies or forming apparatus.

Another object of the invention is to provide an improved method for making sheet metal articles with air circulation louvers, according to which manipulation of the material of the articles in a particular manner results in the provision of the louvers.

Still another object of the invention is to provide an improved method of making sheet metal articles with air circulation louvers by torsional displacement or twisting of the material of the articles.

Still another object of the invention is to provide an improved method of providing louvers in sheet metal articles and which method is adapted for making a wide variety of articles such as wheel structures, wheel covers, brake drum cooling devices, impellers or fans, and the like.

It is yet another object of the invention to provide an improved method of making louvered fluid impellers, generally.

Other objects, features and advantages of the present invention will be readilyapparent from the following detailed description of certain preferred embodiments thereof taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a fragmentary radial sectional view through a wheel structure embodying features of the invention;

FIGURE 2 is a fragmentary radial sectional view through a modified wheel structure embodying the invention;

FiGURE 3 is a fragmentary outer face elevational view of a sheet metal blank showing the same in an intermediate stage in the process of making a louvered wheel structure according to the present invention;

FIGURE 4 is a sectional view taken substantially on the line IV-IV of FIGURE 3;

FIGURE 5 is an outer face elevational view of the blank of FIGURE 3 after the same has been operated upon to form the louvers thereon;

FIGURE 6 is a fragmentary radial sectional view through anther wheel structure showing yet another modification;

FIGURE 7 is a fragmentary side elevational view of the cover shown in FIGURE 6;

FIGURE 8 is a fragmentary side elevational view of still another modified louvered cover structure;

FIGURE 9 is a fragmentary radial sectionalview through another wheel structure showing the invention as adapted to a trim ring structure;

FIGURE 10 is a fragmentary outer side elevational view of the trim ring of FIGURE 9 showing the blank therefor in an intermediate stage of production;

FIGURE 11 is a fragmentary outer side elevational view of the trim ring showing the same after the louvers have been completed;

FIGURE 12 is a fragmentary radial sectional detail view of a wheel structure showing the adaptation of the invention to a brake drum cooling ring device;

FiGURE 13 is a fragmentary outer side elevational view of the brake dnlm cooling ring member of FIG- URE 12 in a preliminary stage of manufacture;

FIGURE 14 is a fragmentary side elevational view similar to FIGURE 13 but showing the air circulation promoting ring member following final formation of the louvers thereof;

FIGURE 15 is a face elevational view of an impeller or fan structure embodying louvers made according to the present invention;

FIGURE 16 is a fragmentary enlarged transverse sectional detail view taken substantially on the line XVI XVI of FIGURE 15;

FIGURE 17 is an enlarged fragmentary, substantially segmental face elevational view of a blank from which an impeller according to the present invention and as shown in FIGURE 15 is made and showing the blank as it appears at an intermediate stage in the making of the impeller; and

FIGURE 18 is a fragmentary transverse sectional dc.- tail view taken substantially on the line XVIII-XVIII of FIGURE 17.

As one example of a sheet metal structure provided with louvers according to the present invention, there is shown in FIGURE 1 a wheel cover 2% constructed and arranged to be applied to the outer side of a vehicle wheel such as an automobile wheel including a disk spider wheel body 21 supporting a multi-flange drop center tire rim 22 arranged to carry a pneumatic tire 23. The wheel body has a central dished bolt-on flange 24 which is arranged to be attached to a brake drum 25 of a vehicle axle to which the wheel may be secured vas by means of attachment bolts or cap screws 27.

For attaching the same to the wheel, the cover member 20 has a central dished bolt-on flange 28 which is arranged to be secured to the bolton flange 24 of the wheel body by the attachment screws 27. About the bolt-on flange 28 the cover has a generally axially outwardly bulged annular portion 29 which may bepro vided at its radially inner side with a suitable series of radially inwardly projecting retaining bumps or protrusions 3d for attachment over the bolt-on flange portion of the cover 20 of a hub cap cover member 31.

Joined to the outwardly bulged portion '29 of the cover by means of an intermediate portion 32 is an outer marginal extremity annular portion 33 which is of a diameter for overlying the outer side of the tire rim 22 and providing for the periphery of the cover a substantially rib-like reinforcement. The intermediate portion 32 of the cover comprises a symmetrical plurality of louver-like vanes 34 disposed in an annular area of the cover with the radially inner ends thereof joining the bulged cover portion 29 and the radially outer ends thereof joining the outer marginal cover portion 33. The length of the vanes 34 is such as to substantially overlie the juncture of the wheel body 21 with the tire rim 22 and more particularly air circulation openings 35 provided by the wheel body at such juncture. All of the vanes 34 are uniformly tilted in the same direction with the maximum til-t throughout the intermediate portions, considered lengthwise, of the van-es while the respective opposite ends of the vanes merge into the connected portions of the cover.

It will be observed that the inner ends of the louver vanes 34 are connected to an annular generally axially inwardly directed adjacent portion or juncture flange structure 37 at the radially outer side of the bulged cover portion 29, thereby affording a stiffening and reinforcing juncture with the inner ends of the vane louvers.

At their outer ends the vane louvers 34 are connected to a generally radially inwardly directed narrow curved reinforcing flange 38 providing juncture at the radially inner margin of the outer marginal cover portion 33.

Each of the v-ane louvers 34 is preferably of a generally sinuous, ogee shape longitudinally. By the construction and relationship of the vanes 34, in rotation of the wheel in service, air circulation is promoted by the vanes through the wheel openings 35 and the cover through openings between and separating the vanes.

According to the present invention the vanes 34 of the cover member 20 are provided by an improved method involving generally shaping a sheet metal blank and then torsionally manipulating the blank to provide the vane louvers. To this end, referring to FIGURES 3 and 4, the cover member 20 is initially drawn in a sheet metal blank of appropriate gauge and material, such as stainless steel or brass having suitable working characteristics. In the pressing or drawing operations, all of the general contours of the cover member 20 are provided to afford the desired profile, as preferred in the finished cover. In this, the cover body portion 29 and the reinforcing flange 37 thereof, as well as the cover marginal portion 33 and the reinforcing flange 38 thereof are completed to the arcuate, substantially stiff and rigid final form thereof.

However, the intermediate portion 32 of the cover 20 in which the louver-like vanes 34 are to be provided is formed of annularly continuous shape but transversely of a generally bulged and preferably sinuous or ogee shape, generally conformable to the ultimate ogee shape of the vanes in the longitudinal direction thereof. The thus formed radially sinuous intermediate cover portion 32 is subdivided by means of uniform narrow slots 39 into equal segments or sections from which the vanes 34 are to be formed. Although in FIGURE 3 the slots 39 are shown as extending radially, it is to be understood that they may be arranged in any preferred angular relation to the radial such as diagonal in one circumferential or rotary direction or diagonal in the opposite circumferential o-r rotary direction, cutting across the sinuous profile of the intermediate portion 32 of the cover member 20.

After the cover pressing or drawing operations have been completed, and the cover member 20 has been suitably finished as by polishing and plating, or the like, the louver vane tilt is imparted to the vane sections 34. This is accomplished by the simple expedient of relatively torsionally oppositely turning the radially inner and outer portions 29 and 33 of the cover about a common axis. Since the inner or cover body portion 29 and its reinforcing juncture flange 37, and the radially outer marginal cover portion 33 and its reinforcing juncture flange 38, are relatively stiff and thus resistant to distortion, while the relatively narrow vane sections 34 are individually relatively flexible, the vane sections 34 yield during the relative rotation of the cover portions 29 and 33. As a result there is a tendency for the vane sections 34 to yield and distort, with stretching along one side of each of the vane sections and a tendency to buckle at the other side with a consequent turning or tilting of the vane section 34 outwardly at the stretched side thereof and inwardly at the opposite side thereof, depending upon the direction of relative torsional movement of the cover parts during the torsional manipulation thereof to effect the vane tilting action.

For more ready comprehension of the vane-forming operation, arrows A and B have been superimposed upon FIGURES 3 and 5. In FIGURE 3, the arrows are in radial alignment at opposite ends of one of the slots 39. This indicates the relative disposition of the respectively outer and inner cover parts 33 and 29 before the relative torsional displacement movement thereof. In FIGURE 5 it will be observed that the arrows A and B are relatively offset in the direction of the directional arrows adjacent thereto, indicating approximately the distance to which the cover portions 29 and 33 have been torsionally relatively displaced for deflecting the vane portions 34.

Since the vanes 34 are connected in one piece with the cover body portion 29 and the outer cover marginal portion 33, they resist the torsional movement of the two annular cover parts to which connected but are forced to yield and are thus uniformly twisted and take a set in the deflected condition to which they are forced by the relative turning displacement of the cover parts. The amount of twisting and relative displacement and thereby tilting desired in the vanes 34 can be controlled by the total distance to which the cover portions 29 and 33 are relatively torsionally rotated and displaced.

While the cover portions 29 and 33 may both be torsionally rotatively relatively displaced simultaneously, it is more practical in most instances to hold one of the cover portions 29 or 33 stationary while the other of the cover portions is relatively rotationally turned or displaced, the end result being the same. By reason of the bulged, ogee sinuous transverse cross-sectional shape of the intermediate cover portion 32, stretching of the louver portions 34 is accommodated while the radially inner and outer portions of the cover with which the louver vanes are connected remain constantly in their relative radial spaced relation.

In FIGURE 4 is shown in full outline the position of the vane sections 34 before the tilting of the vanes, while in dash outline is shown the tilted condition of the vanes after the annular cover portions have been relatively rotatively displaced to the limited extent desired. In FIGURE 1, the unstressed, undeflected condition of the vanes is indicated in dash outline, while the vanes are shown in full outline in their tilted, set, service condition.

Since the intermediate portion 32 of the cover in which the vanes 34 are formed is of sinuous transverse contour before the vanes are twisted into their tilted condition, ample material is provided for the slight elongation in the vanes that occurs during the relative turning displacement of the annular radially inner and outer cover portions. This relieves the inner and outer cover portions 29 and 33 and thereby also the reinforcing flange portions 37 and 38 thereof from any substantial radial stresses that would tend to distort the same.

- In FIGURES 1 and 5, the vanes 34 are shown as tilted at one side toward the outer side of the cover and at the other side uniformly tilted toward the inner side of the cover. In order to effect reverse tilting of the vanes, the cover portions 29 and 33 must be relatively torsionally rotated in the opposite direction to that shown by the directional arrows in FIGURE 5. In this way, the direction of tilt of the vanes can be simply and accurately controlled merely by the direction of relative turning of the cover portions. Since the metal of the vanes takes a permanent set at the conclusion of the relative turning displacement of the cover portions, the vanes hold their tilted relationship permanently in the cover.

An important advantage attained by the present invention, insofar as finishing of the cover is concerned, resides in the fact that the entire surface of the article including the portion of the article in which the louver vanes are to be formed can be finished as by polishing and plating even before the slots dividing the vanes are cut. Thereafter, the polished vane area may be free from any further die contact and thus possible marring since only the slot forming punches will engage the same and thereafter only the inner and outer relatively rigid portions of the article are engaged by the torsionally twisting or relative displacing means or die structure.

In the modification of FIGURE 2, is shown how the invention is adapted to be applied to not only a cover 40 but also a wheel body 41 both of which are, of course, made from suitable sheet metal, the cover of a relatively thin readily drawn type of sheet metal while the wheel body 41 is made from a sheet metalof substantially heavier gauge adapted to withstand the carrying loads that a wheel body must endure in service.

The wheel body 41 has a central bolt-on flange 42, a reinforcing nose bulge 43, and a marginal axially extending attachment flange 44. The latter flange is attached to the base flange of a tire rim 45.

In the present instance the wheel body 41 is provided with a uniform annular series of wheel openings 47 separated by integral air circul-ationpromoting louver vanes 48 in a portion of the wheel body intermediate the marginal attachment flange 44 and the nose bulge 43 and preferably including the radially outer side of the nose bulge. Since the nose bulge 43 substantially reinforces the body of the wheel, and the axially extending marginal attachment flange 44 is relatively rigid, the louver vanes 43 can be provided in the wheel body 41 in substantially the same manner as described for provision of the louver vanes 34 in the wheel cover of FIGURE 1.

i111 providing the vanes 48 in the wheel body, the wheel body is initially stamped substantially completely to the contour or profile desired, but with the portion intermediate the nose bulge 43 and the marginal flange 44 of radially sinuous, preferably ogee form in order to afford extra material for the elongation occurring in the louver vanes 4% as an incident to the twisting, tilting displacement of the same during formation by relative torsional, rotary displacement of the radially inner and outer portions of the wheel body with which the vanes are joined. As shown in FIGURE 2 in dash outline, the original contour of the intermediate vane portion of the wheel body is in an annularly continuous form while after the relative coaxial turning or rotational displacement or twisting of the radially inner and outer portions '43 and 4d of the-Wheel body, the vanes 43 tilt to substantially equal opposite outer and rear sides of the original annular disposition of the vane segments. The result is a uniformly vaned wheel body which in the rotation of the wheel effects air circulation through the wheel and more especially through the wheel adjacent to juncture of the. wheel body with the tire rim for efliciently cooling the brake drum of an axle to which the wheel may be attached in substantially similar manner as shown in FIGURE 1, that is by attachment of the bolt-on flange M. to a vehicle hub having a brake drum thereon.

The cover 40 is preferably made from a single sheet of sheet metal such as stainless steel or brass and has a circular inner cover body portion 49 joining an annular series of symmetrically disposed and formed air circulating vanes 54} at a reinforcing juncture flange 51. At their outer ends, the vanes 50 are connected as by means of a reinforcing flange 52 to a marginal annular cover portion 53 having an under-turned flange portion 54 provided with a series of generally axially inwardly extending resilient flexible retaining fingers 55 provided with retaining terminals 57 for retainingly gripping an intermediate flange of the tire rim.

The cover louver vanes 50 are formed in substantially the same manner as described for formation of the vanes 34 of the cover 2t} and for formation of the vanes 48 of the Wheel body 41. That is, the cover is provided with a radially sinuous or ogee shape in the portion to have the vanes 56, and the vanes are defined by separating slots 58 in the cover. Then, after the cover 40 has been properly finished, inclusive of the vane portion of the cover while the same is in the dash outline position shown,

the inner and outer portions 49 and 53 of the cover are relatively torsionally rotatably displaced to deflect and stretch and set the vanes in the tilted louver vane condition relative to the rest of the cover.

It will be observed that the vanes 59 are located generally opposite to the vanes 48 of the wheel body so that in the rotation of the wheel air will be efliciently circulated through the cover and through the Wheel body.

In the modification of FZGURES 6 and 7, an arrangement is shown wherein a wheel cover 60 made from thin sheet metal is provided with louver vanes 61 in an intermediate cover portion 62 and intermediate initially or originally non-radial slots die. It will be observed that the intermediate annular area comprises one divergent section joined to a central substantially rigid cover portion 53 and to a radially outer divergent annular portion 64, the latter having a turned under flange structure provided with cover retaining fingers 65 for engagement with a flange of a tire rim 67, with the louvered intermediate portion generally opposite wheel openings 68 provided at juncture with the tire rim by a load sustaining wheel body 69.

. The intermediate louvered section 62 of thecover has the slots 63a formed initially straight but non-radial. Then by relatively torsionally displacing the radially inner cover portion 63 and the radially outer cover portion 64- the slots are distorted into generally sinuous or S shape and their edges are displaced laterally by twisting deflection of the louver portions 61. It will be observed that in the present instance the intermediate section 62 is initially of a generally ogee or sinuous curved shape. It will also be observed that in this instance the radially outer end portions of the slots 61a are displaced farther from the radial position, as indicated by comparison of the arrows A with the arrow B in FIGURE 7.

In the modification of FIGURE 8 a wheel cover 70 is depicted which in most respects is similar to the wheel cover 60 and is adapted to be applied and removed with respect to a vehicle wheel of the same kind as shown in FIGURE 6. vane louvers 71 is provided in a divergent annular portion 73 of an intermediate generally dished part of a cover, including a second divergent portion 73, and an inner or central portion74. In this instance, the divergent cover portion 73 is at the radially inner side of the annular dished cover part. The several louver vanes 71 are separated by slots 75 running generally transversely of the annular divergent cover portion 73. In the present instance, in order to afford substantial reinforcement and to efiect a pleasing ornamental arrangement, the louver portions 71 are of peaked rib formation.

Best results. are attained by having the cover portion 72. of transversely generally bulged or curved shape, preferably of generally ogee transverse cross-section. Initially the slots'75 are formed substantially straight but non-radial. Then, by torsionally relatively displacing the radially outer and radially inner cover portions 73 and 74, substantially as indicated by the reference arrows A and B, to thereby relatively displace the opposite ends of the louver portions 71 and of the slots 75 the slots and the louver portions are not only distorted into generally sinuous or S or ogee shape, but the edges at one side of the louver portions are bent generally axially outwardly and at the opposite side are bent generally axially inwardly so as to effect the vane louver structure thereof uniformly entirely around the intermediate cover section 72.

In FIGURES 9, 10 and 11, there is depicted a cover in the form of a trim ring which is made according to the method of the present invention. The trim ring 80 is adapted to be applied to the outer side of a vehicle wheel including a drop center multi-flange tire rim 81 carried by a disk spider wheel body 82 and adapted to carry a central hub cap 83. Herein, the trim ring 80 is of a diameter to overlie the tire rim and the juncture thereof In the cover 70', an annular series of air.

with the wheel body and air circulation openings 84 provided by the wheel body adjacent to such juncture.

The trim ring cover member 80 includes an outer marginal convex rib-like annular portion 85 and a radially and axially inner underturned rigidifying small radius shoulder portion 87 from which project integral extension spring fingers 88 for retaining engagement with a flange of the tire rim intermediate the cover portions 85 and 87, the trim ring cover member is provided with a uniform series of transverse slots 89 which initially may be substantially radial as seen in FIGURE and in dash outline in FIGURE 11 but which are in the final form of the trim ring member of generally sinuous, ogee shape as shown in full outline in FIGURE 11. Such a relationship of the slots 89 is attained by relatively torsionally displacing the cover portions 85 and 87 about a common axis as depicted by the reference arrows A and B in FIGURE 11. Thereby the material between the slots 89 of the intermediate annular portion of the cover, which is of preferably arched, ogee transverse contour, is distorted and bent uniformly to provide louver vanes 90 having one side tilted generally axially outwardly and the opposite side tilted generally axially inwardly.

It may be noted that because of its annular form, the trim ring cover member 80 may be made from strip stock by rolling the sheet metal of the strip into ring form and in such rolling affording the blank with the transverse contours as described. The ends of the rolled ring-form strip may be butt welded. The slots 89 may be cut in the blank as an incident to the rolling or after the ring has been formed.

Application of the invention to the formation of a brake drum cooling ring structure 95 is illustrated in FIG- URES 12, 13 and 14. Such a cooling ring is constructed and arranged to be mounted across the gap between a tire rim 97 and a brake drum 98 of a vehicle wheel structure. The tire rim is supported by a wheel body 99 that is secured as by means of attachment screws 100 to the brake drum. Wheel openings 101 between the tire rim and the wheel body aflord air circulation for cooling the brake drum and the ring member 95 is adapted to effect a circulation of air through the wheel for cooling the brake drum.

As shown, the cooling ring member 95 is of a generally U-shaped cross-section and is of annular ring form adapted to be made by die press or rolling method of manufacture from suitable thin gauge sheet metal such as stainless steel, brass or other suitable strip or sheet material. At its radially inner side the cooling ring has a generally axially extending annular wall 102 having at its axially outer end a turned brake drum engaging flange 103. Joined to the radially inner wall 102 by a generally radially extending and axially inwardly facing intermediate wall 102a is a radially outer, generally axially extending wall 104 having a turned shouldering flange 105 that is adapted to bear against the inner terminal flange tip of the tire rim.

The radially outer wall portion 104 of the cooling ring member is preferably of transversely bulged, preferably generally ogee contour and is sub-divided by a series of transverse slots 107 into a plurality of louver vane air circulation promoting strips or sections 108 which aflord a certain amount of resilience for the outer wall 104 that enhance the resilient, compression, tensioning interengagement of the wall portion 104 through the flange 105 with the tire rim in the assembled relationship with the wheel.

In forming the louvers 108, the transverse slots 107 are relatively angularly displaced torsionally into generally sinuous, ogee relationship from a generally straight condition as shown in FIGURE 13 into the finished sinuous condition in FIGURE 14. The angular displacement is visually indicated by the index arrows A and B. In effecting the torsional displacement of the slots 107 and thereby also of the louver strips 108 the 8 substantially rigid portions 103 and 104, of the ring member are relatively torsionally displaced for thereby longitudinally stretching and tiltably bending and displacing the louver sections 108, causing one of the sides thereof to tilt inwardly and the opposite side to tilt outwardly into the desired louver form.

In connection with FIGURES 15-l8, adaptation of the invention to the making of an impeller or fan structure for moving fluid is depicted. In the exemplary form of the invention selected for illustration, an impeller member 110 has a central hub portion 111, an outer marginal frame ring or flange 112 and an intermediate impeller blade or vane section 113. The impeller 110 is adapted to be constructed from a single piece of sheet metal of appropriate grade and gauge. Depending upon the size and service requirements of the unit, stainless steel sheet, brass sheet or other self-sustaining sheet metal may be utilized.

By having the impeller of generally cup shape, attained by having the outer marginal flange 112 of generally frusto-conical or flaring funnel-like shape certain advantages such as rigidity in minimum diameter, tunnelling of impelled or suction fluid, and the like, accrue.

In the illustrated embodiment of the invention, the impeller blade section 113 is provided with a uniform series of impeller blades 114 which are angled obliquely, uniformly and are bowed on respective transverse axes to afford eflicient fluid scoops for impelling fluid in the rotation of the impeller. In the present instance, the arrangement is such that upon rotation of the impeller counterclockwise as viewed in FIGURE 15 movement of fluid will be from the inside of the impeller cup toward the outer side as indicated by the directional arrow in FIGURE 16.

In the eflicient and economical formation of the vanes 113 of the impeller, without the use of any forming dies, but entirely by a metal stressing and stretching and bending and setting operation, the impeller is initially spun or stamped into a shape substantially as depicted in full outline in FIGURE 18 and in the combination full and dot dash outline of FIGURE 16. It will be observed that the vane section 113 is of transversely concave, convex, generally curved, ogee contour. Such contour is selected for the particular operating characteristics or final shape desired in the finished vanes 113.

At uniformly spaced intervals, the intermediate vane portion 113 of the impeller is provided with radially extending slots 115 thereby dividing the same into generally outwardly tapering increasing width vane sections. Near the framing margin 112, the slots 115 are provided with enlarged head end portions or circumferentially extending cut-outs or recesses or notches 117, thus affording a generally T-shape through the slots as best seen in FIGURE 17. This also affords at the radially outer ends of the longitudinally curvate ogee vane sections rounded corner shoulders 118 with narrow central connecting necks 119 with the marginal flange 112.

Completion of the impeller formation is effected by relatively angularly torsionally turning or displacing the central attachment flange portion 111 relative to the outer marginal rigid flange portion 112. In order to afford vanes 114 tilted for impelling fluid movement in the direction indicated by the directional arrow in FIGURE 16, the radially inner and outer portions 111 and 112 of the impeller blank are relatively angularly offset as indicated by the reference or indexing lines A and B in FIGURE 17. One of the portions 111 and 112 of the cover may be held stationary while the other of the portions is torsionally displaced, or both of such portions may be simultaneously turned in relatively opposite directions. The extent of the relative angular turning of the portions 111 and 112 will determine the pitch of the vanes 114. Furthermore, the direction of relative torsional displacement of the portions 111 and 112 will determine the direction of tilt or pitch of the vanes 114.

9 For example, if the vanes 114 are to be tilted or pitched oppositely to the position thereof shown in FIGURES and 16, or as indicated in dash outline in FIGURE 18, then relative turning of the portions 111 and 112 should be reversed from that indicated by the relative off-setting of the arrows A and B in FIGURE 17. The sheet metal between the end portions of the vane sections takes a permanent set in the pitched condition of the vanes. All of the vanes are of uniform contour and pitch, if the vane sections are initially of uniform shape.

Additional variations in the specific shape of the vanes 114 may be effected by having the radial slots 115 formed spirally or angled from the radial. The width and the spacing of the slots 115 are other variable factors affording choice as to the shape or pitch characteristics of the ultimate vanes. Variationsas to the fluid impelling action of the vanes 114 in their radial extent may be precalculated by appropriately modifying the original sinuosity of the intermediate section 113 of the impeller. The sinuous formation of the intermediate section 113 affords adequate material for stretching of the vane sections as an incident to the angular deflection of the vanes, without distorting the inner attachment flange 111 or the outer framing flange 112 of the impeller.

While in all forms of the invention specifically disclosed, it will be noted that the area in which the twisted vane louvers are formed is bounded radially inwardly and outwardly by relatively radially fixed portions of the article, similar results may be obtained where the vane sections are attached only at one of their ends while the other ends are free. In such a structure the free ends may be clamped between gripping dies and the free ends and the attached ends of the vane strips then relatively torsionally displaced or offset to effect the twisting tilting, stretching of the vane sections to afford the uniformly louvered final condition thereof.

Although it is generally more expedient to provide the vane louvers on an intermediate portion of the article, or as extensions from a circular portion, the louver vanes may be made as individual strips which after the twisting, stretching, tilting, shaping thereof may be attached to a supporting portion of an article. In any event, whether the louver vanes are made as individual strips or as parts in one piece of a sheet metal article, during the shaping of the louvers the ends of the louver strips remain on the same diameter even though there is an elongation of the strips incident to the torsional shaping action wherein the 'ends move further apart as permitted by the arched, preferably ogee longitudinal shape of the strips before the louver twisting manipulation thereof.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

1. In a method of making a sheet metal article, shaping an elongated strip bowed intermediately on transverse axis and with the ends of the strip a predetermined distance apart, and while stretching the strip, relativelylaterally offsetting the end portions of the strip to effect tilting of the strip intermediate the end portions thereof.

2. In a method of making a sheet metal article, the steps of subdividing a portion of the article into a series of separated elongated strips with the strips intermediately bowed on transverse axes, and relatively offsetting the end portions of the strips while stretching the strips whereby to effect tilting of the strips into louver form.

3. In a method of making a sheet metal article, shaping the article to provide an annular area of generally dished transversely curved shape, subdividing the annular area along transverse lines but leaving unsevered annular portions connecting the respective opposite ends of the portions of the annular area between the subdivisions, and relatively torsionally displacing those unsevered annular portions of the article at the opposite ends of the W subdivisions whereby to alter the length of and transversely tilt the subdivisions into louver vane shape.

4. In a method of making a sheet metal article, shaping the article to provide an annular area having oppositely dished annular transversely curved portions merging into one another, slotting across one of said portions and into the other of said portions, and relatively displacing said portions about the axis of the annulus to distort the areas of said slotted portion intermediate said slots into tilted condition.

5. A method of making a circular sheet metal member which comprises drawing a sheet metal blank to provide radially inner and radially outer angularly disposed annular substantially stiff portions. and an intermediate radially sinuous and annularly uniform portion, transversely slotting said intermediate portion, and relatively turning said annular stiff portions to twist the sections of said sinuous intermediate portion intermediate said slots to provide air circulation vanes.

6. A method of making a sheet metal article, comprising shaping circular radially inner and radially outer relatively rigid portions and an intermediate annular portion of curved cross-section, finishing the surface of the article, thereafter slotting across the intermediate portion at uniform intervals, and then relatively turning said inner and outer portions about the axis of the article and setting the separated areas of said intermediate portion in tilted vane positions.

7. The method of making a vehicle wheel body which comprises stamping a heavy gauge sheet metal blank to provide a circular body portion having an annular nose bulge and a continuous annular marginal portion including an attachment flange and an intermediate annular portion of substantial width and arched in cross-section, slotting said intermediate portion transversely and relatively turning said nose bulge and said marginal portion and marginal flange about a common axis and thereby twisting the portions of the sections of the intermediate portion between the slots therein into air circulating vanes.

8. A method of making a wheel cover which comprises drawing a thin sheet metal blank into a cover body comprising a circular annular and substantially rigid inner portion and a circular annular substantially rigid outer marginal portion and an intermediate annular portion of substantial width and arched thereacross, slotting said intermediate portion transversely into a plurality of sections which are connected at their ends to said rigid portions, and relatively torsionally turning the inner and outer portions about a common axis and thereby twisting and longitudinally altering the lengths of the intermediate sections into louver-like vanes.

9. In a method of making a cover out of flat sheet metal for a wheel, the steps of forming the cover into peripheral and central circular portions with a dished annular intermediate area defined by radially extending divergent sections, forming in one of said sections slightly non-radial slots radiating from said central portion, and circumferentialiy displacing said slotted section with reference to one of said portions to distort each of said slots, as a consequence thereof, into a generally sinuous shape.

1G. In a method of making a cover out of flat sheet metal for a wheel, the steps of forming the cover into peripheral and central circular portions with a dished annular intermediate area defined by radially extending divergent sections, providing one of said sections with slots radiating generally from said central portion, -circumferentially displacing said slotted section with reference to its original position relative to one of said portions to distort each of said slots, as a consequence thereof, into a generally sinuous shape, and contemporaneously with the distortion of the slots into sinuous shape also distorting the material between the slots into sinuous peaked ribs with the slots in valleys separating the ribs.

11. In a method of making a trim ring, the steps of rolling a strip of sheet metal into ring form and with the radially inner and radially outer margins turned into rigidifying structures, slotting the intermediate portion of the strip, and relatively torsionally displacing the radially inner and radially outer marginal portions to twist the sections intermediate the slots into louver shape.

12. A method of making a brake drum cooling ring structure, which comprises shaping a sheet metal body into substantially annular hollow channel shape, forming transverse elongated openings in an annular portion of said body and with spaced apart annular substantially rigid portions to which the ends of areas intermediate said openings are integrally connected, and relatively torsionally displacing said rigid portions of said body to twist and longitudinally alter the areas intermediate said openings into air impelling vane form.

13. In a method of making an impeller, the steps of shaping a sheet metal blank to provide a central portion and an annular outer marginal continuous flange with an intermediate radially sinuous portion, forming T-shaped slots in said intermediate portion with the heads of the Ts adjacent said marginal flange, whereby to divide said intermediate portion into a series of vane sections, and relatively angularly displacing said central and marginal flange portions to twist said vane sections into angular relation to said central and marginal flange portions.

References Cited in the file of this patent UNITED STATES PATENTS 840,457 Hill Jan. 1, 1907 1,370,083 Blaekrnore Mar. 1, 1921 1,583,787 Gersman May 11, 1926 1,958,484 Lyon May 15, 1934 1,986,836 MacNeille Jan. 8, 1935 2,597,010 Lyon May 20, 1952 2,684,521 Morrison July 27, 1954 2,731,193 Lall Jan. 17, 1956 2,779,424 Lyon Jan. 29, 1957 2,828,838 Lyon Apr. 1, 1958 

